The present invention relates generally to dental prostheses and, more particularly, to a dental prosthesis including an implant, an abutment which is attachable to the implant, and a crown which is attachable to the abutment and the implant such that the joint defined between the abutment and the implant is covered and effectively sealed.
As is well known in the art, dental prostheses are commonly used in the dental field to address extensive damage to teeth caused by injury or disease. A typical dental prosthesis comprises an implant, an abutment and a crown. The implant itself generally comprises a metallic component which is implanted or embedded into the bony structure of a patient's mouth subsequent to the removal of the damaged tooth alone or in combination with one or more adjacent teeth. The installation of the implant is typically initiated by forming a hole in the bony structure and then embedding the implant into the bony structure by screwing the implant into the hole via threads formed on an exterior of the implant.
After the implant has been embedded into the bony structure, the bone normally recovers and grows around the implant, thus resulting in bone/implant integration. To enhance the integration of the implant into the bone, the implant may be coated with a surface finish such as etched titanium and/or a biocompatible coating such as hydroxylapatite (HA). Subsequent to the embedding of the implant into the bony structure, the abutment is attached to the implant. Such attachment may be accomplished through the use of a cement, by the engagement of complementary male and female threads formed on or in the abutment and implant, or by the mating of corresponding tapers or other geometries formed on or in the abutment and implant.
When attached to the implant, a portion of the abutment extends above the gum line of the patient for purposes of facilitating attachment of the crown to the implant. If the implant is embedded into the bony structure such that the implant is completely disposed below or submerged within the gum line of the patient, the attachment of the abutment to the implant requires a second surgical procedure for purposes of accessing the implant. However, if the implant is embedded into the bony structure in a manner wherein a portion thereof protrudes above the patient's gum line, then the attachment of the abutment may be accomplished without the need for the second surgical procedure, thus requiring only the initial surgical procedure to complete the implantation or embedding process.
As was previously indicated, the crown of the dental prosthesis is attached to that portion of the abutment which extends above the patient's gum line. In the prior art, crowns are fabricated and installed in accordance with well-established procedures which include taking a transfer impression of the exposed portion of the abutment to establish with precision its configuration and orientation, thus insuring a complete attachment of the crown thereto. The exposed portion of the abutment to which the crown is attached may have the natural form of a prepared tooth, or an artificial form of a particular geometry adapted to achieve a secure attachment of the crown. The attachment of the crown to the abutment is typically accomplished through the use of an adhesive and/or cement, or through the engagement of corresponding male and female threads on or in the crown and abutment to each other. The attachment of the crown to the abutment completes the assembly of the dental prosthesis.
As will be recognized from the aforementioned description of the dental prosthesis, the assembly thereof results in the formation of several joints. These joints include the joint formed by the attachment of the crown to the abutment, and the joint formed by the attachment of the abutment to the implant. Of these joints, that joint considered most important in relation to the long-term viability of the prosthesis is the joint between the implant and the abutment which is commonly referred to as the implant abutment joint or “IAJ”.
Recent research in the dental field has suggested that the IAJ plays a key role in bone loss around the implant. Though such bone loss has not been well studied or well documented, it is believed to be a common occurrence which is at least partially attributable to the IAJ serving as a site for bacterial invasion and colonization. Over time, such bone loss can compromise the integrity of the implant or cause its failure by breaking loose from the bony structure into which the implant is embedded.
Obviously, such failure, in addition to providing inconvenience and discomfort for the patient, is of serious medical concern due to the resulting bone loss or mutilation potentially rendering the installation of a replacement implant difficult or impossible. The joint formed by the attachment of the crown to the abutment is also susceptible to bacterial invasion which contributes to bone loss around the implant.
The present invention addresses the susceptibility of the IAJ and the crown/abutment joint to bacterial infestation by providing a dental prosthesis which is configured to effectively cover and seal these joints. In addition, the dental prosthesis of the present invention also prevents micro-movement between the abutment and the implant at the IAJ which, under the forces of mastication (i.e., chewing), can result in the development of micro-gaps at the IAJ. Such micro-gaps can harbor bacteria which can lead to inflammation and, ultimately, failure of the implant.